Question

What is a cell.............

Answer 1

Cell is the structural and functional unit of living organisms.

It is considered as structural unit because all living organisms are made up of cell. Whereas a single cell can perform multiple function that's why regarded as functional unit of life.

Robert Hooke first discovered the cell in 1665 with the help of his self made microscope.

According to cell theory :

• All living organisms are made up of cells.

• All cells come from pre-existing cells by cell division.

Each and every organism is made up of cells.

• Organisms having single cells are considered as Unicellular organisms.

• Organisms having multiple cells are considered as Multicellular organisms.

Different cells have different size and shape.

• Their shape can be cuboid, disc like etc.

• Their size range is between 1 - 100µm.

Cells are of two types,

》 Eukaryotic cells

• They are generally bigger in size.

• Nuclear region is well defined and surrounded by a nuclear membrane.

• Single chromosome is present.

• Linear DNA is present in them.

• They are multicellular.

• Example :- Human beings, plants etc.

》Prokaryotic cells

• They are smaller in size.

• Nuclear region is not well defined and not surrounded by a nuclear membrane.

• More than one chromosomes are present in it.

• Circular DNA is present in them.

• They are unicellular.

• Example :- Bacteria, blue-green algae etc.

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Answer 2

Answer: -

•Cell is the smallest units in a living things.

•Unicellular:Living things made up of a single cell.

•Multicellular:Living things made up of a many cells.